Originally developed to assist with IPM and varroa mite counts, this screened bottom board has also proven valuable as part of a well planned ventilation system. In New England climates use this with a slatted rack to buffer the brood box from the open bottom. May be left open over-winter with some careful considerations, otherwise have a plan in place to close it up during the cold seasons. It also helps to close it up during installation of a new queen to keep her pheremone scent strong while getting established.